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How to Test Nitrogen in Soil

earth image by Alison Bowden from

Knowing what nutrients are present at what levels in your soil is an all-important step to growing healthy flowers, vegetables or grass. Nitrogen is an important element in fertile, healthy soil. Often, soils that are acidic, with a pH level of less than 7, are lacking in nitrogen. If you find your soil lacking in nitrogen, adding a nitrogen-rich fertilizer will help replenish this missing nutrient.

Perform the soil test in late summer or early fall. This will allow enough time to add nitrogen-rich fertilizers to the soil, if needed, and let them fully integrate into the soil before the next planting season.

Remove any debris from the surface of the test area.

Use a soil probe to collect samples throughout the area to be tested. Push the probe into the soil, at a depth of 4 to 6 inches.

Pull the soil probe out of the soil, leaving the sample intact. Transfer the sample from the probe to a clean container.

Repeat the sample-gathering process in three to six different locations throughout the area, adding them to the previously gathered samples. Multiple samples will give you a more accurate reading.

Air dry the soil sample, in its container or on a baking sheet, until it is completely dry.

Break up any clumps by working the soil, with your hands, until it is a powdery consistency. Remove any debris you may find.

Measure out 1/8 cup of the dried soil and weigh it with a kitchen scale and write down the weight.

Pour the weighed soil sample into the plastic container. Pour 1/8 cup of distilled water into the container. Place the lid on the container and mix the soil and water by shaking vigorously.

Fold the filter paper in half, then in half again. Bend the paper until it forms a cone shape.

Place the filter cone, pointed end down, into the plastic container, until it touches the bottom of the container.

Wait until the water seeps up through the filter. Collect a sample using the eye dropper.

Remove a nitrate test strip from the package and place it on a flat surface. Place one or two drops of the water from the eye dropper onto the test strip.

Wait 60 seconds for the results. Hold the test strip up to the color-coded guide on the test strip package. Match the color of your test strip with the corresponding color. The number associated with your color is the amount of nitrogen in your soil sample, as indicated in ppm (parts per million).


Performing a soil test every three to five years is recommended to keep up to date with changes in your soil's pH and nutrient levels.


Home soil test kits are convenient, but are not always as accurate as tests performed by professionals at soil testing facilities.

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